1. Field of the Invention
The present invention relates to a scanning image projection apparatus that scans laser light to project images.
2. Description of the Related Art
For scanning image projection apparatuses using a laser light source, the international standard IEC60825 and respective countries place limits on output powers of these light sources (laser light source). Specifically, IEC60825 desires that the output power of the light source be set to or below Class 2 at which safety is secured by blinks due to aversive reaction of a viewer if a light flux from the light source directly enters a viewer's eye.
However, the output power of the light source set to or below Class 2 may reduce brightness of images projected on a projection surface such as a screen, which may impede good image observation.
Therefore, Japanese Patent Laid-Open No. 2005-10616 discloses a scanning image projection apparatus that separates positions of spots of an R-light flux, a G-light flux and B-light flux from each other in consideration of a pupil of a viewer. Moreover, Japanese Patent Laid-Open No. 2005-114985 discloses a scanning image projection apparatus that has thereinside a long optical path length sufficient to secure safety if an viewer looks directly at a light exit part of the apparatus
However, it is necessary for the scanning image projection apparatus disclosed in Japanese Patent Laid-Open No. 2005-10616 to enlarge a scanning area of the light fluxes by a scanning device so as to separate the positions of the spots of the respective color light fluxes. This results in enlargement of the scanning device and a requirement to increase the output power of the laser light source because of reduction of light use efficiency (time efficiency).
Moreover, the scanning image projection apparatus disclosed in Japanese Patent Laid-Open No. 2005-114985 does not allow placement of any device in an area where the optical path is formed, which increases the size of the apparatus.